07.06.14 5:01 AM ET

One challenge facing documentary filmmaker Steve James as he prepared his movie on the life of Roger Ebert is that so much was already known about, and so much had been heard from, the famous subject. The best-known film critic in history was nothing if not prolific, churning out hundreds of reviews for print, television, and the Internet, as well as two dozen books on subjects that included not only movies but also computers and rice cookers—capped by his startlingly unguarded autobiography, Life Itself, in 2011.

James’s film was originally intended to be a straightforward adaptation of that book, but Ebert passed away in 2013, just one month into shooting. Ironically or not, that broadened the film’s horizons—and in ways that probably would have pleased Ebert greatly. It helped make the film of Life Itself genuinely worthy of the title, and genuinely worth seeing. Skepticism crumbles in the face of so moving a story so beautifully told, the kind of movie Roger Ebert would likely have loved.

What may impress you most about Ebert if you watch the film—in a movie theater or “On-Demand” cable or the web or wherever—is the generosity of the man, the unselfish way Ebert gave freely of his time and attention even as he, to employ a woefully trite phrase, was living his own life to the fullest, and later, when his physical self failed him. The hardships he suffered—cancer of the thyroid, loss of his jaw, and narrow escapes from death years before it came—seem especially unfair in light of his joy at living.

Near the end, he told his wife Chaz, a very important part of his life and of the film, that he was ready to go, even though he had successfully adapted to the loss of his voice, his mobility, even his ability to eat. Without telling Chaz, Ebert signed a “Do Not Resuscitate” order, prohibiting doctors from bringing him back from a brink he had already visited.

Life Itself is not a litany of either Ebert’s misfortunes or his virtues, however. Anyone who makes his living as a critic will earn enemies, and even friends of Ebert’s acknowledge his fallibilities. He was egotistical even as a child, it is noted, infatuated with the sight of his name on a rubber stamp and later as a byline. “He could be a real big baby when he didn’t get what he wanted,” says an associate, and another notes that Ebert’s partnership with fellow Chicago critic Gene Siskel, on their dueling-critics TV show, brought out a “petulance” in him they hadn’t seen before.

Roger and Gene weren’t “pretending” to disagree or even, at least in their early years on the air together, to dislike each other. But their animosity made for terrific TV and, strangely or not, formed the basis of a friendship that, Ebert wrote in a tribute to Siskel, “grew into love.” Siskel developed a brain tumor late in the 1990’s and in February of 1999, died at the age of 53. Only-child Ebert came to realize, Chaz Ebert says, that Siskel had become “the big brother he never had.” In a note to Siskel’s amiable wife, Marlene, Ebert wrote, “I’ve never met a smarter or funnier man.”

Kevin Horan

The parts of Life Itself that evoke the Siskel-Ebert years (the billing was established by a coin toss) are fitfully and sometimes bitterly funny, including outtakes from promos the two taped for episodes of the show, needling and deriding one another mercilessly. During a flight to Los Angeles, perhaps for one of their many appearances with Johnny Carson on The Tonight Show, Siskel played a practical joke on Ebert that was hugely irresponsible and equally hilarious. No spoiler alert needed, because we’re not giving it away here.

Perhaps the gag was a way of getting even with Ebert not for past disputes but because Ebert appeared never, ever to tire of the spotlight or the workload, whereas Siskel gave the impression of having other things to do. Both, however, grew very comfortable in their roles and lived in mutual angst that the other half of the team might not want to renew when contract time came around.

James does not include in his film excerpts from the Hollywood movies that contained Siskel-Ebert references, including the sodden 1998 bomb Godzilla that featured an Ebert-like mayor of New York and a Siskelish top aide. Earlier, a two-headed dragon in the Ron Howard flop Willow was known, at least around the set, as the “Ebersisk.” But we do see again the clip of Ebert trouncing the film Three Amigos on the Carson show while its star, Chevy Chase (speaking of petulance), made childish faces behind him on the couch.

Much later, and ever a man of his time, Ebert not only adapted to the computer age but also made it work for him when cancer robbed him of his distinctive voice and disarmingly feminine telegenic appearance. Ebert founded a website he referred to as “my blog” and invited other critics, all of course lesser-known than him, to contribute. That web site still exists, watched over faithfully by Chaz.

In the interests of full disclosure, I must confess that I’ve been an (unpaid) contributor to the web site and that Life Itself is the first movie or TV show I’ve ever reviewed that I helped finance, albeit meagerly; as a member of the Ebert “blog” team, I contributed a non-whopping $25 to the production. It was supposed to be $125 but the damn computer mucked it up. There will be no return on the investment, which was meant as a tiny tribute.

I was, in fact, one of the lucky recipients of the inexhaustible generosity documented in the film. Licking my own wounds repeatedly—after being shabbily screwed by new executive arrivals at the depleted Washington Post—I was surprised to hear from Roger, who’d learned of my plight. From his perch at his laptop keyboard, Roger lectured me sternly on the evils of pity-partying and, more helpfully, nursed me out of the only case of writers’ block I’d had in 40 years.

I knew I was only one of many Ebert beneficiaries, but all those emails, which I’ve saved, made me feel like a close friend rather than the mere acquaintance that I had been. Roger and I had crossed paths many times over the years, and when Gene became too ill to appear on the Siskel & Ebert show, Roger asked me to fill in on two episodes, assuring me that Gene had approved the choice. As Life Itself reveals, Gene was secretive about the severity of his cancer; he died as I was leaving Chicago for the trip back East, even though it had been assumed and announced that he would return to the show.

It’s stated in the film, incidentally, that Washington Post executive editor Ben Bradlee “went after Roger hard” once he’d won the Pulitzer Prize, the first film critic to do so. Ebert rebuffed the offer. As it happens, Roger’s paper, the Chicago Sun-Times, made me an offer some years later to be its TV critic, and I was close to signing when Bradlee, grumbling, agreed to meet the Sun-Times’ offer, whining as if parting with his own money. A footnote—to history!

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Roger and I did look a lot alike at various stages of our lives, both perpetually battling our bulks (we were fat), but weren’t much alike. Roger told me he liked everything he ever wrote and I hated everything I ever wrote. He was gregarious and sociable, enjoying the company of entourages whenever he went to Cannes or some other film festival. He simply loved the world and the people in it, and enjoyed both to the maximum—sometimes to his detriment, as in his early years at the Sun-Times when he went on frequent booze binges with “the boys” and was also addicted to big-bosom’d babes, a yen that led naturally to an association with nudie filmmaker Russ Meyer and their collaboration on the absurd Beyond the Valley of the Dolls.

He stopped drinking in 1979, he says in narration, and we learn it was at an AA meeting that he met Chaz—the love and, he says, the salvation of his life. Their love story is one of the most moving threads in the narrative, and we see not only the joys they shared but also the trauma of devastating illness. In one of several brave editorial choices, James includes a long scene in which Chaz and two helpers argue with Roger, returning home from one of innumerable hospital stays, about getting out of his wheelchair and climbing five or six stairs. He becomes angry, intransigent, furiously scribbling notes; Chaz meets determination with determination.

Love can mean forcing your mate to get off his ass and climb the damn stairs.

The film is full of vibrant details, one of them a literal jigsaw puzzle that Alfred Hitchcock supposedly gave to Marilyn Monroe and somehow ended up in the possession of actress Laura Dern, who then gave it to Ebert. Jigsaw puzzles, of course, figure significantly in the Orson Welles masterpiece Citizen Kane, about which Ebert wrote a book-length essay that was a marvel of insight and revelation, and implicitly a rebuke to anyone—especially the New York cineaste set—who considered him a lightweight peddling glib reviews on television.

Martin Scorsese is among the celebrated film figures appearing in the documentary, and he chokes back tears recalling how Ebert, and Siskel, helped salvage his career during a low point. We all have our low points, including Roger, but even then, he found remarkable reserves of courage. James doesn’t underscore the moments with cinematic embellishments (in fact, most of the music on the soundtrack is awful) and doesn’t need to.

I will always be grateful to Roger Ebert, and I hope I told him so during our exchanges of emails. I will always be glad I saw Life Itself, even though parts of it are very hard to watch, not just because they’re emotionally wrenching, but because they reveal some of the pain that Roger endured. Having a tube jabbed into an open wound in your throat is clearly not pleasant. You may want to look away but James and his camera, wisely, do not.

Roger always said he considered his life to be a movie in which he starred. It was a great life and now, literally, it is a great film. That’s not my twenty-five bucks talking; it’s my heart.